Method of coating leather with polymers containing hydroxyl groups and the resulting article



United METHOD OF COATLQG LEATHER WITH PSELY- MERS CONTAINING HYDROXYL GROUKS AND THE RESULTING ARTHILE No Drawing. Application March 21, N55 I Serial No. 495,804

22 Claims; (Cl. 117-76) This invention relates to coated leather products and to processes for producing them. It is particularly concerned with coated leathers having composite multi-layer coatings which have improved adhesion to the leather and to each other and excellent softness and flexibility even under extremes of cold and heat.

U. S. Patent 2,204,520 discloses a procedure for applying aqueous dispersions of emulsion-polymerized acrylic acid esters or the like to leathers. Such dispersions in practice are frequently provided with pigments and are generally covered with one or more final lacquer top coats. The aqueous dispersion serves to fill imper factions and to level the surface of the leather and to improve the adhesion between any lacquer top coats applied and the leather. The coatings obtained from the aqueous dispersions disclosed in the patent provide good adhesion to many leathers and particularly to snuffed, buffed and split leathers. However, on some types of full grain leathers such coatings have poor adhesion. This poor adhesion is particularly noticeable on leathers which have been subjected to certain types of fatliquoring, such as sperm oil, or which. have acquired such a large amount of fatty deposits on the surface of the leather'dur ing fatliquoring as to in effect provide a resist to aqueous coating compositions.

It has now been discovered that improved adhesion may be obtained between the leather and polymers applied to it by means of an aqueous vehicle if the polymer contains hydroxyl groups. In accordance with the present invention, it has been found that the application of aqueous dispersions of certain resins containing hydroxyl groups to the leather provides improved adhesion to full grain leathers as well as to buifed and split leathers and'also improves the resistance to scufiing resulting from rubbing action against the finished leather surface as Well as improvement in resistance to wet molding operations.

To impart the improved qualities in the finished leathers in accordance with the present invention, the leather is coated with an aqueous dispersion of a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising at least 3% by weight of a mono-- meric compound having the structure of the following general Formula I:

where A is O- or --S, and R is a straight or branched chain alkylene group having from 2 to 10 carbon atoms, C2H4,AC2H4;, '-C2H4N(R')C2H4, O1- C H N(R )(R )(X)C H where R is H, CH C H or C H OH and R and R are methyl, ethyl, or hydroxyethyl(-C H OH) groups and X is a negative radical, such as OH, Cl, Br, I, CH SO and tolyl sulfonate.- A preferred group is that of the others having the Formula H:

II cn,=cn ocn on where x may be 2; tobut is preferably 3 to 6, the efiiciency generally being at a maximum when x is 5.

will

Examples of these monomers are:

18-Hydroxyethyl vinyl sulfide ,B-Hydroxyethyl vinyl ether 3-hydroxypropyl vinyl sulfide S-hydroxypentyl vinyl ether 6-hydroxyhexyl vinyl ether S-hydroxyoctyl vinyl ether 10-hydroxydecyl vinyl ether B-Hydroxyethylaminoethyl vinyl ether (N-B-hydroxyethyl-N-methyl)aminoethyl vinyl ether Hydroxyethyldimethyl(vinyloxyethyDa m m o n i u m hydroxide Thiodiglycol monovinyl ether Thiodiglycol monovinyl sulfide Diethyleneglycol monovinyl ether The higher hydroxyalkyl vinyl others may be made in the same way as the lower ones are by the Reppe processes disclosed in various patents and publications.

The polymers must not be water-soluble. Where the hydroxy ether or hydroxy sulfide monomer that is polymerized is' of such character that ayhomopolymer produced therefrom is appreciably water-soluble, it is necessary to copolymerize such a monomer with at least one other copolymerizable monoethylenically unsaturated monomer which is of a character that will render the final copolymer insoluble in water. Many of the hydroxylcontaining monomers have such a large proportion of hydrophobic groups in their molecule that homopolymers thereof will necessarily be water-insoluble and in such cases, a homopolymer can be applied to leather for accomplishing the purpose of the invention. Frequently, however, it is preferable from the cost stand point. to copolymerize the hydroxy monomer with a cheaper and more readily available comonomer. Preferred compositions of the invention are, therefore, those copolymers of from 3% to 30% of the hydroxyl-contai'ning ether or sulfide monomer or of a mixture of such monomers, the balance of the copolymer being formed of other less expensive comonomers.

Other polymerizable compounds containing a single ethylenically unsaturated group that may be copolymerized with the others or sulfides to produce binary, ternary, etc. copolymers include the esters of acrylic acid or methacrylic acid or the dimer of methacrylic acid with monohydric alcohols such as methyl, ethyl, butyl, octyl, dodecyl, cyclohexyl, cyanoethyl, benzyl, phenylethyl, and the like: diesters of itaconic acid and the above alcohols; esters of maleic, fumaric, or citraconic acids with the above alcohols; vinyl esters of carboxylic acids such as acetic, propionic, butyric, and the like; vinyloxyalkyl esters such as vinyloxyethyl acetate, etc.; vinyl ethers and sulfides such as ethyl vinyl ether, ethyl vinyl sulfide, butyl vinyl ether, octyl vinyl ether; methacrylonitrile or acrylonitrile; acrylamide, or methacrylamide, and N-alkylsubstituted amides of these types; vinyl toluene, vinyl naphthalenes, such as 4-chloro-1-vinyl naphthalene, and styrene.

The emulsifiers or dispersing agents that may be used for preparing the monomeric emulsions before copolymerization or dispersions of the polymer after polymerization may be of anionic, cationic, or non-ionic type or a mixture of two types may be used.

Suitable anionic dispersing agents include the higher fatty alcohol sulfates, such as sodium lauryl sulfate, alkylaryl sulfonates, e. g., sodium or potassium isopropylbenzene sulfonates or isopropyl naphthalene sulfonates, alkali metal higher alkyl sulfosuccinates, e. g., sodium octyl sulfosuccinate, sodium N-methyl-N-palmitoyltaurate, sodium oleyl isothionate, alkali metal salts of alkylarylpolyethoxyethanol sulfates or sulfonates, e. g., sodium 3 t-octylphenoxypolyethoxyethyl sulfate having 1 to 5 oxyethylene units.

Suitable cationic dispersing agents include lauryl pyridinium chlorides, cetyl dimethyl amine acetate, and alkyldimethylbenzylammon'ium' chlorides in which the alkyl group has from 8 to 18 carbon atoms, such as octyl, decyl, dodecyl or octadecyl, t-octylphenoxyethoxyethoxydimethylbenzylammonium chloride. 5

Suitable non-ionic dispersing agents include the following: alkylphenoxypolyethoxyethanols having alkyl groups of about seven to eighteen carbon atoms and 6 to 60 or more oxyethylene units, such as heptylphenoxypolyethoxyethanols, octylphenoxypolyethoxyethanols, methyloctylphenoxypolyethoxyethanols, nonylphenoxypolyethoxyethanols, dodecylphenoxypolyethoxyethanols, and the like; polyethoxyethanol derivatives of methylene linked alkyl phenols; sulfur-containing agents such as those made by condensing 6 to 60 or more. moles of ethylene oxide with nonyl, dodecyl, tetradecyLt-dodecyl, and the like mercaptans or with alkylthiophenols having alkyl groups of six to fifteen carbon atoms; ethylene oxide derivatives of long-chained carboxylic acids, such as lauric', myiistic, palmitic, oleic, and the like or mixtures of acids such as found in tall oil containing 6 to 60 oxyethylene units per molecule; analogous ethylene oxide condensates of longchained alcohols, such as octyl, decyl, lauryl, or cetyl alcohols, ethylene oxide derivatives of etherified or esterified polyhydroxy compounds having a hydrophobic hydrocarbon chain, such as sorbitan monostearate containing 6 to 60 oxyethylene units, etc.; also ethylene oxide condensates of long-chain or branched chain amines, such as dodecylamine, hexadecylamine, and octadecylamine, containing 6 to 60 oxyethylene groupsiblock copolymers of ethylene oxide and propylene oxide comprising a hydrophobic propylene oxide section combined with one or more hydrophilic ethylene oxidesections.

Particularly valuable resin dispersions are obtained by emulsifying a mixture of (a) one or more of the hydroxylcontaining monomers above and (b) one or more monomeric esters of acrylic, methacrylic, or itaconic acid or mixtures of these acids in water and polymerizing the mixture while it is in the emulsified form. The monomeric esters whichhave proven to be most satisfactory are the alkyl esters in which the alkyl group contains one toeight carbon atoms and which are exemplified by the following: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, isoamyl, tert-amyl, hexyl, heptyl, n-octyl, and Z-ethylhexyl acrylates, methacrylates, and itaconates' 1 V The .polymerizable emulsions can be prepared at temper-atures from 0 C. to aboi1t l00 C., but intermediate temperatures are'much preferred; Thus, when the preferred copolymers with esters are made with the esters in which the alkyl group contains one to four carbon atoms a temperature from about C. to about 60 C. is employed whereas a higher temperature; e. g.,' 30 C. to 80 C., is recommended when esters containing five to eight carbon atoms in the alkyl group are copolymerized. Peroxidic free-radical catalysts, particularly catalytic systems of the redox type, are recommended. Such systems, as is well known, are combinations of oxidizing agents and reducing agents such as a combination of potassium persulfate and sodium metabisulfite. Other suitable peroxidic agents include the per-salts such as the alkali metal and ammonium persulfates and perborates, hydrogen peroxide, organic hydroperoxides such as tert-butyl hydroperoxide and cumene hydroperoxide, and esters such as tert-butyl perbenzoate. Other reducing agents include Water-insoluble thiosulfates, hydrosulfites, tertiary amines, such as triethanolamine, thiourea, andthe salts, such as the sulfates, of metals which are capable of existing in more than one valence state such as cobalt, iron, nickel,- and copper. The'most convenient method of preparing the dispersions of copolymers comprises agitating an aqueous suspension or emulsion of the mixture of copolymerizable monomers and a redox catalytic combination at room temperature without the application of external heat. The amount of catalyst can vary but for purposes of efficiency from 0.01% to 3.0%, based on the weight of the monomers, of the peroxidic agent and the same or lower proportions of the reducing agent are recommended. In this way, it is possible to prepare dispersions which-contain as little as 1% and as much as 60% or even more of the resinous copolymer on a weight basis. It is, however, more practical, and hence preferred, to produce dispersions which contain about 30% to 50% resin-solids.

Preferably a pigment is introduced into the aqueous coating dispersion and the amount of pigment introduced may vary from thatequivalent to about 10% to by weight of the polymer. Generally, the pigment is first dispersed in water (to a concentration of about 30% to 45%) by means of a non-ionic or anionic dispersing agent or, a mixture of both types thereof. Any of the dispersing agents mentioned above may be used. In addition, a small amount of a protective colloid may be included to thicken and! or stabilize the suspension and prevent 'the pigment 'from settling out. Examples of such colloids include methyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, sodium, potassium or ammonium alginates, ammonium or alkali metal salts of homopolymers .and copolymers of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and the like, such as ammonium polyacrylate, ammonium salts of copolymers of styrene and maleic acid, sodium methacrylate, and so on.

. The aqueous dispersion of the polymer or copolymer with or without a pigment dispersed or suspended therein may be applied to the leather at a solids concentration of 10% to 50% (including the weight of. polymer and pigment, if any). It may be applied by any suitable equipment such as by brushing, swabbing, or spraying onto the leather. After application of the dispersion, it may be dried on the leather either by drying in the ambient atmosphere or at somewhat elevated temperatures up to 50 C. ,The amount of copolymer applied on the leather varies widely with the type of leather and the ultimate finish desired. For most purposes, the amount applied per thousand square feet of the leathermay vary from 1 to 15 pounds. i 7

It is believed that the improved adhesion obtained on leather by the application of the polymers containing the hydroxyl groups is attributable to some chemical or physico-chemical reaction between such groups and the protein molecules of the leather or with'the tanning agent or fatliquor deposit on the leather, or possibly on some joint reaction with two or more of these substances. However, it is not intended that the invention be limited by any particular theory of operation.

For some purposes, the leather product carrying the single coating obtained from the application of the aqueous dispersion of the polymer containing hydroxyl groups with or without pigment may serve as a suitable finished product. 7 For example, this may be the case when it is desired only to impart a water-repellent surfaceto the leather and the polymer applied by the aqueous dispersion is of highly hydrophobic character either as the result of the presence of a long-chain hydrocarbon group in the hydroxyl-containing monomer or as the result of such a long-chain hydrocarbon group in the comonomer or as a result of long-chain hydrocarbon groups in both of such monomers. However, in many cases, it may be desired to apply one or more additional coatings of a lacquer type over the coating obtained from the aqueous polymer dispersion. Any suitable lacquer composition may be applied such as-those which comprise as the film-forming material an addition polymer of "vinyl, acrylic or related types, a cellulose derivative such as a nitrocellulose or cellulose organic acid esters such as celluluose acetate, cellulose acetate butyrate or-the like. The lacquers may comprise aplastici zer the film-forming agent itself is.

7 Eli:

not adequatelyflexible. When asingle lacquer top coating is applied over the coating obtained fromthe aqueous polymer dispersion, it may be clear, it may be dulled by a filler or other suitable agent, such'as a water-insoluble soap, like aluminum stearate or silicas, or it may be colored with a white or suitably colored pigment. Preferably at least two lacquer top coatings are applied in succession over the coating obtained from the aqueous dispersion. When two such lacquer coatings are applied, the first is preferably pigmented to augment the color and covering obtained by the pigment, if any, applied by the coating from the aqueous dispersion and the second lacquer coating is preferably clear or merely dulled to provide the glossiness or flatness desired in the final surface.

Each of the subsequently applied coatings should be dried before any later coating is to be applied and drying may be effected as before either at normal room temperature in the ambient atmosphere or at somewhat elevated temperatures up to 50 C.

If desired, the leather may be embossed after the coating applied in the aqueous dispersion has been dried on the leather and before subsequent lacquer coatings are applied, or embossing may be applied at any time after subsequent coatings are applied but preferably before the last or final coat is applied. Such embossing should, in all cases, be applied to the coated leather in a dry condition.

As the vinyl or acrylic addition polymer that may be used for the film-forming component of the subsequently applied lacquer or lacquers, there may be used one or more homopolymers or copolymers of the following monoethylenically unsaturated compounds: vinyl chloride, vinyl acetate, vinyl propionate, vinylidene chloride, esters and nitriles of acrylic and methacrylic acids such as acrylonitrile, methacrylonitrile, and the alkyl esters of acrylic or methacrylic acid in which the alkyl group may be methyl, ethyl, propyl, isopropyl, butyl, octyl, dodecyl, hexadecyl, and octadecyl. Besides the above homopolymers and copolymers, polyvinyl acetals such as polyvinyl acetal itself, polyvinyl butyral or partially hydrolyzed homopolymers. and copolymers of vinyl acetate, vinyl propionato or of acrylic and methacrylic esters may be used. Such compounds contain reactive hydroxyl and carboxyl groups. Other polymers containing reactive groups may be used provided the polymers do not contain sufiicient reactive groups to render them insoluble in the organic solvent employed. Such polymers include the copolymers containing up to 50 mole percent of ,B-hydroxyethyl vinyl ether or of B-hydroxypentyl vinyl ether, up to 50 mole percent of aminoethyl acrylate, aminoethyl vinyl ether or N-methylor N-ethylaminoethyl vinyl ether, or up to 30 mole percent of a vinyl pyridine, such as 2- vinyl pyridine, or 4-viny1 pyridine, or of an amide, such as acrylamide, methacrylarnide, N-methyl acrylamide, or

of an acid, such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, and the dimer or trimer of methacrylic acid, or the like.

When a plasticizer is used, it may be a polyester, polyamide, or polyester amide such as may be obtained by the condensation reaction of a dibasic acid with a polyol or a polyamine. More particularly, the plasticizer (which may be termed a polymeric plasticizer) may be obtained by reacting combinations of materials of the general types noted below:

I Glycols (or other polyols) and dibasic acids II Amino alcohols and dibasic acids HI Glycols, diamines and dibasic acids IV Glycols, amino alcohols and dibasic acids V Amino alcohols, diamines and dibasic acids VI Amino acids, glycols and dibasic acids VII Amino acids, amino alcohols and dibasic acids VIII Amino alcohols, glycols and-dibasic acids IX Amino alcohols, dibasic acids and hydroxycar- 'boxylic acids 1 I It is advantageous to use a small excess of the alco holic-hydroxyl-containing constituent in preparing the polymers.

Examples of polyols include trimethylol methane and erythritol. Examples of glycols are ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, dodecamethylene glycol, lzl2-octadecanediol and pentaglycol.

Examples of dibasic carboxylic acids are malonic, succinic, glutaric, adipic, fi-methyladipic, pimelic, suberic, azeiaic, sebacic, undecanedioic, brassylic, isophthalic, hexahydroterephthalic, p-phenylene diacetic and acetonedicarboxylic acid.

Any amino alcohol having at least one hydrogen atom attached to the amino nitrogen atom may be employed including aromatic amino alcohols, e. g. p-hydroxymmhylbenzylamine, 4-hydroxymethyl-4-aminomethyldiphenyl and p-aminophenylethyl alcohols; aliphatic amino alcohols, e. g. 5-aminopentanol-l:-amino-S-methylhexanol- 1,4 p-aminophenyl cyclohexanol, hydroxyethoxyethoxyethylamine, and N-(B-aminoethyl)-ll'--(omega--hydr0xyhexyl)-aniline.

The preferred amino alcohols are of formula l-lO-R-NI-I Where R represents saturated divalent hydrocarbon radicals with a chain length of at least two carbon atoms. Amino alcohols Which fall within this group include ethanolamine, S-aminopropanol, 4-aminobutanol, -aminohexanol, and IO-aminodecanol.

Any diamine may be employed, which contains at least one hydrogen atom attached to each amino nitrogen atom. The preferred diamines are of formula NH RNH where R represents saturated divalent hydrocarbon radicals with a chain length of at least two carbon atoms, e. g. ethylenediamine, hexamethylenediamine, 3-methylhexamethylenediamine, and decamethylenediamine. However, aromatic diamines such as m-phenylenediamine may also be used.

Any polymerizable monohydroxy monocarboxylic acid or ester-forming derivative thereof may be employed. The preferred hydroxy-acids are of formula I-lO-R-COOH where R represents saturated divalent hydrocarbon radicals, e. g. 6-hydroxycaproic, lO-hydroxydecanoic, and l2-hydroxystearic acid.

Any polymerizable monoaminomonocarboxylic acid 0 ester-forming derivative thereof may be employed including 6-aminocaproic, 9-aminononanoic, and ll-aminoundecanoic, and IZ-aminononanoic, caprolacteum, etc.

The organic solvents that may be used include ketones such as acetone, methyl ethyl ketone and dioxane; hydrocarbons such as xylene, toluene, benzene as well as parailinic or naphthenic types such as solvent naphthas, esters such as ethyl, propyl, butyl and amyl acetate as well as ethoxyethyl acetate, butoxyethyl acetate and the like, or ethers such as butyl ethyl ether. The solvent may comprise a mixture of several types. It a polyisocyanate is used as suggested hereinafter, a solvent should be of a type which does not contain an active hydrogen.

The pigments that may be employed in the lacquers or the aqueous copolymer dispersion or in both of these media include red iron oxide, chrome green, molybdate chrome orange, phthalocyanines, such as copper phthalocyanine, titanium dioxide, lithopone, chrome yellow, ultramarine blue, red cadmium, yellow cadmium, organic toners and lakes, and so on.

It has been found that the adhesion between the leather and the coating thereon, especially when several *7 the .driedpolymer coating obtained fromthe aqueous dispersi'onI It may also be applied as a component in any of the subsequently applied lacquers or it may be applied to the dried coated leather after any of the subsequently applied lacquers. Preferably, if a polyisocyanate is employed, it is incorporated in the first lacquer coating applied over the polymer coating obtained from the aqueous dispersion.

Examples of the polyisocyanates that may be employed include especially the hydrocarbon polyisocyanates such as ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, naphthalene diisocyanates, benzene 1 :3 5triisocyanate, toluene-2 4: 6

triisocyanate, ethylbenzene 2:4:6 triisocyanate, monochlorobenzene 2:4:6 triisocyanate, triphenylinethane- 4:4':4"-triisocyanate and diphenyl 214:4 triisocyanate, toluene 2,4 diisocyanate, 4,4 diisocyanato biphenyl, 3,3 dimethyl 4,4 diisocyanato biphenyl, and 3,3 'dimethoxy 4,4" diisocyanato biphenyl. The polyisocyanates have various reactivities, some being much slower than others. For example, diphenylmethane-4,4-diisocyanate is highly reactive whereas the 3,3-. dimethoxy-4,4-diisocyanato-biphenyl is relatively slow. To compenate for the difference in reactivity, the proportion added may be increased for the slower ones and decreased for the faster ones or basic catalysts, such as tertiary amines may be included, especially with the slower ones. Mixtures of the polyisocyanates may be used of which preferred combinations are mixtures of.

toluene-2,4-diisocyanate With either 3,3- dimethyl-4,4 diisocyanato-biphenyl or 3,3 dimethoxy 4,4-diisocyanato-biphenyl.

When one or more lacquer coatings are to be applied after the application of the polyisocyanate, it is preferred that the drying of the polyisocyanate in place on the coated leather should not be so prolonged or at such high temperatures that all the isocyanate groups are completely reacted. By so leaving the active isocyanate groups of the drying of subsequent lacquer coatings provides the opportunity for reactive combinations of isocyanate groups with any reactive groups that may be present in such subsequently applied lacquers.

It appears that, when a polyisocyanate is used, the improved adhesion between the several layers of the coating and between the leather is at least partially attribut able to some reaction between the polyisocyanate, the leather, the film-forming component and possibly the plasticizer in the several coatings. stood, however, that the application to the leather of the aqueous dispersions of polymers containing hydroxyl groups as defined hereinabove imparts improved adhesion between lacquer coatings and the leather and shows improved adhesion between the leather and the polymer deposited from the aqueous dispersion. This adhesion is for most purposes fully adequate even without the employment of a polyisocyanate. The application of the polyisocyanate, however, may be desirable to obtain even better adhesion for some particular purposes and has also the advantages of increasing the dryness or slipperiness of the top surface of the coated leather. When two lacquer coats are applied over the coating obtained from the aqueous polymer dispersion, the first of such lacquers preferably has the following composition: from to 200 parts by weight of plasticizer, if presentpper 100 parts of the addition polymer or cellulose ester; from 5 to 150 parts by weight of a pigment or mixture of pigments per 100 parts of the film-forming component; from 1% to 65% by weight of a polyisocyanate, if used, this percentage being based on the sum of the weights. of the plasticizer and film-forming component. The amount of solvent employed may be such as to provide a solids concentration (that is materials other than the solvent them: selves) of 2% to 20% by weight The final lacquer coat It should be underr isusually an unpigmented solution (either clearer dulled by aninert delustering filler) of the plasticizer and film forming component, either or both of which may be the same-as1orditferent-from the respective plasticizer and film-forming component of the first lacquer coat. When both lacquer-coats'contain plasticizer; the proportion in the final coating is somewhat less inproportion to the film-forming component than the proportion used in the first lacquer coating. Generally, it is within the proportion-of 15 to 80 parts per 100 parts of the film-forming component. r

In the following examples,which are illustrativeof the'invention, parts and percentages are by Weight unless otherwise specified? Example 1 (a) A dispersion of a copolymer was prepared ,by emul- 'sifying 9'5parts by weight ofethyllacrylate with 5 parts by weight of 2-hydroxye'thyl vinyl ether in about 300 parts by weight of water with about 2 parts by weight of sodium lauryl sulfate and-6' parts by weight of an ethylene oxide condensation product of an .Octyl phenol containing between 30 and 50 oxyethyleneunits per molecule. To the emulsified monomers 0.3% by weight of ammonium'pe'rsulfate, 0.06%jof sodium hydrosulfite, and 1% triethanolarnine were added to catalyze-the copolyinerization which was'carried out fora period of about fifteen minutes during which the temperature'rose from 20 C. to 45 C. a

V (b) Nine parts of red iron oxide are dispersedin 14 parts of water by means of two parts of a suitable, dispersing agent, such as a mixture of equal parts of sodium lauryl sulfate and t-octylphenoxypolyethoxyethanol containing abouti l0 oxyethylene units i n combination with A part of a suitable protective colloid, such as methyl cellulose, :andthe mixture was added to 100 parts of the copolymer dispersion of part; (a) hereof. The resulting pigmented dispersion was swabbed on-several pieces of a full grain upholstery leather and dried at 50C. The coating exhibited excellent adhesion to the leather.

(c) The procedure of parts (a) and (b) hereof is repeated except the 2-hydroxyethyl vinyl ether is omitted so that a dispersion of a homopolymer of ethyl acrylate is produced and applied to the full grain upholstery leather. The coating on the leather could be pulled off the leather intact.

Example 2 (a) A mixture of 40 parts of red iron oxide, six parts of a plasticizer consisting of a polyester obtained by the reaction of sebacic acidwith an excess of propylene glycol and having a number average molecular weight of about 4,000, 2.9 parts by weight of a copolyrner of vinyl chloride and 10% vinyl acetate .having a number average molecular weight'of about 40,000, 6.1 parts ethoxyethyl acetate, 25 parts of methyl ethyl ketone and 20 parts of a petroleum solvent consisting of a'mixture of aromatic, naphthenic, and aliphatic hydrocarbons is ground in a ball mill for 24 hours to form a pigment dispersion.

j (b) A. solution is also formed from 3.1 parts of the same plasticizer as above and 5.0 parts of the same vinyl copolymer in 10 parts of ethoxyethyl acetate, 44 parts of methyl ethyl ketone and 34.9 parts of a hydrocarbon solvent largely consisting of xylol.

(c) The solution of part (b) hereof is then mixed with the milled pigment dispersion of part (a) hereof in the ratio of 90 parts of the former to 10 parts of the latter. The resulting'dispersion' is applied to a piece of the coated leather obtained in part (b) of'Example l and dried at 50 C. for about three hours.

(d) Then a clear coating is applied to the coated leather obtained in part (c) hereof by spraying a solution containingabout 1.5% of the same plasticizer (of part (a)) and 5% of the's'ame 'vinyl copolyrner (of part ((1)) in a solvent mixture composed of 10% of ethoxyethyl acetate, 55% methyl ethyl ketone and 35% of a hydrocarbon composed largely of xylene. After applying the clear coating by'spraying, it was dried at 50 C. The final coated leather had a glossy color and was soft and flexible.

Example 3 (a) The procedure of Example 2, parts (a) through (d) is repeated except that 3.0 parts of toluene-2,4-diisocyanate is added to the solution of part (12) thereof. The resulting leather has a drier feel, shows excellent adhesion between the coatings and also between the leather and the several coatings, and is even more resistant to wet molding operation than that obtained without the diisocyanate in part (b).of Example 1.

(b) The procedure of Example 2, parts (a) through (d) is repeated except that 3.0 parts of toluene-2,4-diisocyanate is added to the solution of part (b) thereof and the dispersion obtained in part (c) thereof is applied to the leather obtained in part (c) of Example 1 wherein the full, grain upholstery leather is coated with a homopolymer of ethyl acrylate. The adhesion of the coatings to the leather is fair but special precautions are needed during Wet molding operations to prevent damage to the finished leather.

Example 4 (a) The procedure of Example 1, parts (a) and (b), is repeated except that the monomers are replaced with 80 parts by weight of ethyl acrylate, 15 parts by'weight of n-butyl acrylate and 5 parts of B-hydroxyethylamino etuyl vinyl ether. The dried leather showed excellent adhesion between itself and the coatings.

(b) To the coated leather obtained from part (a) hereof there is applied two lacquer coatings of the same composition as and by the procedure of parts (a) through (d) of Example 2. Excellent adhesion is obtained between the lacquer coatings and the leather.

Example 5 Example 6 (a) The procedure of Example 4(a) is repeated except that the five parts of fi-hydroxyethylaminoethyl vinyl ether are replaced with five parts of (N-B-hydroxyethyl- N-methyl)aminoethyl vinyl ether. 7 Good adhesion is obtained between the coating and the leather.

(b) The product obtained'from part (a) hereof is topcoated as in Example 2, parts (a) to (d) inclusive. Again good adhesion is obtained.

Example 7 (a) A dispersion containing 15% of a copolymer of 70% n-butyl acrylate with 30% 10-hydroxydecyl vinyl ether is pigmented as in Example 1(b), applied to a full grain leather, and dried as in Example 1(b). Good adhesion between the coating and the leather is obtained.

(b) The coated leather is top-coated as in parts (a) through (d) of Example 2. The coated leather shows good adhesion between the lacquer coatings and the leather.

Example 8 (a) An aqueous dispersion containing 20% of a copolymer of 85 parts by weight of ethyl acrylate and parts by weight of S-hydroxypentyl. vinyl ether is pigmented as in Example 1(b) except the red iron'oxide is of the fat-liquoring operations.

. 10 replaced with molybdate chrome orange. After application to the leather and drying as in Example 1(b), the coating shows good adhesion to the leather.

(b) The coated leather of part (a) hereof istop-coated as in Example 2, parts (a) through (d), except that the red iron oxide is replaced with molybdate chrome orange. The coated leather exhibited good adhesion between the lacquer coatings and the leather.

Example 9 An aqueous dispersion containing 20% by weight of a copolymer of parts by weight of n-butyl acrylate' with 15 parts by weight of hydroxyethyldimethyl(vinyloxyethyl)ammonium hydroxide is applied to a full grain leather in the manner described under Example 1, parts (a) and (b) after pigmenting according to that procedure.

Example 10 An aqueous dispersion containing30% by weight of a copolymer of 50 parts of n-butyl acrylate, 40 parts of.

to a leather for the purpose of coating it avoids excessive impregnation of the leather which sometimes occurs when a polymer is applied from an organic solvent solution thereof. It, therefore, avoids the stiffening and the undesirable break and feel of the coated product that are caused by severe impregnation. At the same time, the application of the aqueous dispersion of the polymer has the advantage of enabling the operator to apply the composition containing a large proportion of solids therein without encountering the disadvantages of high viscosity and low mobility which would be encountered if the polymer'wereapplied by the use of an organic solvent solution. In addition, the application of the particular polymers of the present invention by an aqueous dispersion provides improved adhesion for many types of leather, particularly those which have a large amount of fatty deposits on the surface of the leather as a result When lacquer top coatings are applied over the coating applied from the aqueous dispersion of the particular polymers of the invention, improved adhesion is obtained between the lacquer top coating system and the leather as compared to that obtained with polymers: heretoforesuggested to be applied by aqueous dispersion which contain'no'hydroxyl groups.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. As an article of manufacture, a leather having a coating thereonv comprising a water-insoluble linear polymer of monoethylenic'ally' unsaturated molecules comprising (l) 70 to 97% by weight'of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of it monomeric compound having the structure of formu a where A is selected from the group consisting of O- and S, and R is selected from the group consisting of straight and branched chain al'kylene groups having from 2 to 10 carbon atoms, --C H;AC H

Where R is selected from the group consisting of H, CH C H and C H OI-I and R and R are individually selected from methyl, ethyl, and hydrox-yethyl (C H OH groups and X is a negative radical. 2. As an article of manufacture, a leather having a coatmonomeric compound having the structure of formula where x has a value from 2 to 10.

3.'As an article of manufacture, a leather having a coating thereon comprising a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in. which thealkyl group has 1 to 8 carbon atoms and (2) 3% to 30%'by weight of fi-hydroxyethyl vinyl ether.

4. As an article .of manufacture, a leather having a coating thereon comprising a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (l). 70 to.97% by weight of an alkyl esterof an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and.(2) 3% to 30% by weight of {i-hydroxyethylaminoethyl vinyl ether.

5. As an article of manufacture, a leather having a coating thereon comprising a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of ,B-hydroxyethyl vinyl sulfide.

6. As an article of manufacture, a leather having a coating thereon comprising a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of (N-p-hydroxyethyl-N-methyl) aminoethyl vinyl ether.

(1) 70 to 97%'by weight of'an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) about to by weight of B-hydroxyethyl vinyl ether, and, superimposedon said layer, a pigmented lacquer coating comprising a vinyl resin and a plasticizer for the vinyl resin.

7. As an article, of manufacture, a leather having a coating thereon comprising a water-insoluble linear polymer of monoethylenically'unsaturated molecules comprising (1) 70 to 97 by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atomsand (2) 3% to 30% by weight of 5hydroxypentyl vinyl ether.

8. As an article of manufacture, a leather having a multi-layer coating thereon, one layer of which comprises a pigmented water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting'of acrylic, methacrylic, and itaconic acids in which the alkyl group hasl to 8 carbon atoms and (2) 3% to 30% by weight of a monomeric compound having the structure of Formula I as defined in claim 1, and,'superimposed on said layer, at least one lacquer coating comprising a film-forming component.

9. As an article of manufacture, a leather having a multi-layer coating thereon, one layer of which comprises a pigmented water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70.

to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of a monomeric compound having the structure of Formula I as defined in claim 1, and, superimposed on said layer, two lacquer coatings the first of which is pigmented. V

r 10. As an article of manufacture, a leather having a multi-layer coating thereon, one layer of'which comprises a pigmented water'insoluble 'linear' polymer "of 11. As an article of manufacture, a leather having a multi-layer coating thereon, one layer of which comprises a pigmented water-insoluble linear polymer of (l) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) about 5% to 15% by weight of fi-hydroxyethylaminoethyl vinyl ether, and, superimposed on said layer, a pigmented lacquer coating comprising a vinyl resin and a plasticizer for the vinyl resin.

12. As an article of manufacture, a leather having a multi-layer coating thereon, one layer of which comprises a pigmented water-insoluble linear polymer of (l) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) about 5% to 15% by Weight of fi-hydroxyethyl vinyl sulfide, and, superimposed on said layer, a.

pigmented lacquer coating comprising a vinyl resin and a plasticizer for the vinyl resin.

13. As an article of manufacture, a leather having a multi-layer coating thereon, one layer of which comprises a pigmented water-insoluble linear polymer of (1) 70 to 97 by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacryliqand itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) about 5% to 15% by weight of'(N-l3-v hydroxyethyl-N-methyl)aminoethyl vinyl ether, and, superimposed on said layer, a pigmentedlacquer coatingcomprising a vinyl resin and a plasticizer'for the vinyl resin. 8 I

14. As an article of manufacture, a leatherhaving a multi-layer coating thereon, one layer of which comprises a pigmented water-insoluble linear polymer of (1) 70.:to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic,.and itaconic acids in which the' alkyl group has 1 'to 8 carbon atoms and (2) about 5% to 15% by weight of -5.-hydroxypentyl vinyl ether, and, superimposed on' said layer, ,a pigmented lacquer coating comprising-avinyl resin'and a plasticizer for the vinylresin. i '8 15. The method of finishing leather comprising applying thereto an aqueous dispersion of'a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisn'ng of acrylic, methacrylic ,and itaconic acidsin which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of a monomeric compound having the structure of Formula I as defined in claim 1, andthen drying the coated leather..

16. Thernethod of finishing leather comprising applying thereto an aqueous dispersion of a water-insoluble linear polymer of (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of ,B-hydroxyethylaminoethyl vinyl ether, and then drying the coated leathen-f j 17. The method offinishing leathercomprising'applying thereto an aqueous dispersion of a water-insoluble linear polmyer of (1) 'Z0 to 91% by weight of an alkyl ester of an acid selected from'the group consisting of acrylic, methacryliqand itaconic acids in which .thealkyl group has 1' to 8 carbon atoms and (2) 3% to 30% by weight'of fi-hydroxyethylvinyl ether, and'then drying the coated leather.- Y

18. The method of finishing leather comprising applying thereto an aqueous dispersion of a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of a monomeric compound having the structure of Formula I as defined in claim 1, then drying the coated leather, applying thereto a lacquer, at least one of said dispersion and lacquer being pigmented, and drying the lacquer.

19. As an article of manufacture, a full-grain leather having a coating thereon comprising a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of anacid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of a monomeric compound having the structure of Formula I as defined in claim 1.

20. As an article of manufacture, a full-grain leather having a coating thereon comprising a water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) about to by weight of a monomeric compound having the structure of Formula I as defined in claim 1.

21. As an article of manufacture, a full-grain leather having a multi-layer coating thereon, one layer of which comprises a pigmented water-insoluble linear polymer of monoethylenically unsaturated molecules comprising (1) to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of a monomeric compound having the structure of Formula I as defined in claim 1, and, superimposed on said layer, at least one lacquer coating comprising a film-forming component.

22. The method of finishing full-grain leather comprising applying thereto an aqueous dispersion of a waterinsoluble linear polymer of monoethylenically unsaturated molecules comprising (1) 70 to 97% by weight of an alkyl ester of an acid selected from the group consisting of acrylic, methacrylic, and itaconic acids in which the alkyl group has 1 to 8 carbon atoms and (2) 3% to 30% by weight of a monomeric compound having the structure of Formula I as defined in claim 1, and then drying the coated leather.

References Cited in the file of this patent UNITED STATES PATENTS 1,232,620 Stiasny July 10, 1917 2,204,520 Walker et al. June 11, 1940 2,430,479 Pratt et al. Nov. 11, 1947 2,694,688 Hughes Nov. 16, 1954 FOREIGN PATENTS 479,217 Great Britain Feb. 2, 1938 

1. AS AN ARTICLE OF MANUFACTURE, A LEATHER HAVING A COATING THEREON COMPRISING A WATER-INSOLUBLE LINEAR POLYMER OF MONOETHYLENICALLY UNSATURATED MOLECULES COMPRISING (1) 70 TO 97% BY WEIGHT OF AN ALKYL ESTER OF AN ACID SELECTED FROM THE GROUP CONSISTING OF ACRYLIC, METHACRYLIC, AND ITACONIC ACIDS IN WHICH THE ALKYL GROUP HAS 1 TO 8 CARBON ATOMS AND (2) 3% TO 30% BY WEIGHT OF A MONOMERIC COMPOUND HAVING THE STRUCTURE OF FORMULA 